Motor-starter.



G. H. WHITTINGHAM.

MOTOR STARTER.

APPLICATION FILED JAN.20. 1911.

?ate11ted Aug. 24:, 1915.

W'fiawaea' U ITED STATES PATENT OFFICE. v

cnonen H. WHITTINGHAM, or BAN'CROFT PARK, MARYLAND, ASSIGNOR 'ro moNrron' coNTnoLLnn COMPANY, or BALTIMORE, MARYLAND, A GORPORATiON or MARY- LAND.

MOTOR-STARTER.

Specification of Letters Patent.

Application fi led January 20, 1911. Serial No. 603,779.

More particularly, my invention relates to such starters in which the switch members are moved into engagement with their corre sponding contacts by means of positive magnetic pull, as distinguished from that type in which such engagement is produced by gravity.

The object of the present invention is to provide, in connection with a starter of this character, improved means, governed by an abnormal current in the armature circuit, for preventing the operation of such switch or switches until the current shall hav .fallen to a predetermined value.

With the above object in view, the invention consists in the construction and arrangement of parts hereinafter described and claimed, and illustrated in the accompanying drawing, in which Figure 1 is a diagrammatic side elevation of one of my improved automatic switches, parts being shown in section to show the construction; and, Fig. 2 is a diagram illustrating a series of such switches operatively connected to a motor.

Myimproved switch may be used alone or in combination with any desired number of similar switches, as -.will behereinafter explained, and each of these switches may be mounted upon the same or independent switch boards or panels. For convenience of illustration 1, have shown, in Fig. 1, and 7 described, a single such switch mounted upon a panel 1, which may be of slate or other suitable insulating material. To this panel I secure a contact 2 which maybe of any suitable material and construction and which is adapted to be engaged by one end of a switch member or lever 3, pivoted at 4 to a post 5, also secured to the panell. To this lever 3 are attached armatures 6 and 7 at opposite sides of the pivot 4, and mounted upon the panel in position to attract these armatures are electromagnets 8 and 9. The windmg of magnet 8 is connected as by means of a metallic strip 11 on theback ofthe panel to the post 5 and also to this post is connected one end of a resistance coil 10, the other end of which is connected by a wire 11 with the winding of magnet 9. I

It will be observed that magnet 9 is small and has but a few turns of wire thereon, while the winding of magnet 8-comprises many turns and the magnet is also larger and stronger. It will be seen that these two magnets are wholly independent and that they tend to move the lever 3 in opposite direct ons. In the preferred arrangement of my invention, as illustrated in the drawing, it will be noted that by means of the connections 14 and 11 the magnets 8 and 9 are connected in series with each other andwith the resistance 10. These magnets are, however, so designed that a current sufficient to saturate the core of magnet 8 will produce a very feeble magnetization of magnet 9. Consequently, for currents below a certain predetermined value, magnet 8 predominates, and will move thef switch member 3 into engagement with the contact 2, while with large currents, magnet 9 becomes strongly energized, while magnet 8, being already saturated, does not have its magnetization increased appreciably. The normal position of the parts is that shown in Fig. 1, the switch member 3 tending to re; main in this position by gravity. Since the armature 7 is in contact with the magnet 9,

' it will be seen that a heavy rush of current through the apparatus will serve to strongly energize magnet 9 and thus hold the lever in the position shown against the pull of mag net 8 while, when the current falls off, magnet 9 will be weakened to such an extent as to release its armature and permit magnet 8 to move the switch to closed position.

The. operation of "the device in connection with a motor circuit will be apparent from. an inspection ofFig. '2. Where the resistance is to be cut out in several successive steps, as illustrated in this figure, there will, of course, be as many resistance-controlling devices used as there are steps or sections of resistance in the armature circuit, three of such devices being shown in Fig. 2, and being designated A, B and C, respectively. Upon the supply circuit being closed, cur

iio

rent flows from wire 15, along wire 16, through the winding of magnet 9 of switch A, through the resistance 10, and winding of magnet 8 of this switch, thence by wire 17, through magnet 9, resistance 10, and magnet 8 of switch B, thence through wire 18, magnet 9, resistance 10, and magnet '8 of switch C, and thence through wire 19, armature 21, of motor M, to the negative side of the line 20.

22 indicates the shunt field of the motor, and 23 a wire connecting wire 16 with the contact 2 of each of the switches.

"We will suppose, by way of illustration, that the normal current of the motor is 30 amperes. This being the case, each of the magnets 8 would be designed to be saturated by this current or anything greater, while magnets 9 of switches A, B and C, respectively, would be designed to release their arfnatures at current values of 45, 40 and 35 amperes, respectively. We will further suppose that. upon closing the supply circuit, the initial rush of current through the motor starting devices is amperes. This would energize all of the magnets 9 to such an extent that all of the switch arms would be held in the position shown in the drawing and these arms would remain in this position until the current fell to 45' amperes. At this point magnet 9 of switch A would release its armature and the corresponding magnet 8 being still highly energized would move switch member 3 into engagement with contact 2. Current would then flow from wire 16, through wire 23, to contact 2, switch member 3, post 5, connection 11, magnet 8, wire 17, and on through the other devices to the motor thus cutting out magnet 9 and resistancelO of switch device A. When now the current falls to 40 amperes magnet 9 of switch B will release its armature and this switch will close in the same manner cutting out magnet 9 and another section of resistance 10. It will be observed, hdwever, that at the same time, magnet 8 of switch A is short circuited by virtue ofthe closure of switch B and the switch member of switch A thereupon falls to open position by gravity. In the same manner when the current falls to 30 amperes, switch (3 closes and switch is cut out together with the third section 10 of the resistance at switch C. The contact 2 of switch C therefore serves to form the permanent running connection of the motor, magnet 8 of ,this device remaining in the circuit.

In order to insure the magnet 8 releasing the armature 6 when it is short-circuited by the next switch of the series, I provide a thin disk 12 of soft iron or other highly magnetic material and secure it to the end of the magnet core by means of a counter-sunk screw 13. This disk forms a flange which projects laterally from the core, and preferably it extends past the edges of the iron block 8 which constitutes the armature and which comesin direct contact with the disk. I have found that this arrangement effectually prevents residual magnetism from causing the armature 6 to adhere to the pole of the magnet, after the current has been cut off. Preferably, also, the magnet 9 is provided with a similar iron disk 12, as shown in Fig. 1, so that when the current in the coils of the magnet 9 decreases to the point where it is desired to have the switch 'rock to the closed position, the armature 7 will be released without being affected by residual magnetism in the magnet core, and thus the switch will respond more quickly and accurately to changes in current than if the disk were omitted.

It will thus be seen that I have provided means for positively moving the switch members into firm engagement with their respective contacts and also for preventing such movement in case of an abnormal or excess current in the motor circuit and it is thought that the many advantages of my improved arrangement will be readily appreciated by those familiar With such matters.

What I claim is 1. In a motor starter, the combination with the armature circuit, of a resistance in cluded therein, a switch member, electromagnetic means connected with said circuit for positively moving said switch member to short circuit said resistance, and electromagnetic means acting directly upon the switch member itself for holding said mem- I beragainst movement so long as the current in said. circuit exceeds a predetermined amount.

2. In a motor starter, the combination with the armature circuit, of a resistance included therein, a switch member, an electromagnet for moving the same to short-circuit said resistance, and a restraining magnet for holding said member against movement, by direct magnetic pull, so long as the current in said circuit exceeds a predetermined value, the windings of both of said magnets being included in said'armature circuit.

in a motor starter, the combination with the armature circuit, and a resistance, of a switch member for controlling said resistance, and a pair of opposed electromagnets for governing the operation of said switch member, the windings of both of said magnets being connected in series in the armature circuit, one of said magnets being operatively energized only by an abnormal current, and the other of said magnets being energized to its full capacity by a normal current in said circuit.

. 4,. in a motor starter, the combination with the armature circuit, of a resistance normally in series therewith, electromagnetic means for'short circuiting said resistance, and oppositely acting electromagnetic means for holding the short circuiting means against operation, the windings of both said electromagnetic means being included in the armature circuit, said holding means being designed to predominate over said short circuiting means so long as the current in said circuit exceeds a given amount.

5. In a motor starter, the combination with the armature circuit, of a resistance included therein, a switchmember controlling said resistance, an electromagnet for moving said switch member to a position to short-circuit said resistance, said magnet being included in series in said armature circuit, and operatively energized by a normal current therein, and means responsive only to an abnormal current in said armature circuit for preventing the movement of said switch member, the said switch member be ing, under all other conditions, free to move under the influence of said electromagnet.

6. In a motor starter, the combination with the armature circuit, of a plurality of controlling devices associated therewith, each device comprising a resistance and a pair of electromagnets, the windings of all of the electromagnets of all of said controlling devices being connected in series with each other in the armature circuit, one magnet of each device serving,.when energized, to short circuit the resistance associated therewith, and the other magnet of each device serving to hold the short circuiting means against operation so long as the current in the armature circuit exceeds a 'ven amount, the holding magnets of the series of controlling devices being so designed as to become progressively inoperative, whereby the short circuiting means of such devices are permitted to operate, one after the other.

In testimony whereof I afiix my signature,

in presence of two witnesses.

GEORGE H. WHITTINGHAM.

Witnesses:

Fnmx R. SULLIVAN, A. V. Javms. 

